Ink jet recording apparatus with controlled recovery operation

ABSTRACT

An ink jet recording apparatus comprises a timer for measuring an elapse of time from a predetermined measurement start timing, a backup power source for supplying power to the timer when a main power source is turned off, and a controller for changing the content and/or the frequency of a recover operation for recovering and preventing a discharge error in a discharge port for discharging ink on the basis of the elapsed time.

This application is a continuation of application Ser. No. 07/960,281filed Oct. 13, 1992, now abandoned, which in turn is a continuation ofapplication Ser. No. 07/795,246, filed Nov. 15, 1991, now abandoned,which in turn is a continuation of application Ser. No. 07/653,240,filed Feb. 11, 1991, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink jet recording apparatus fordischarging ink from discharge ports of an ink jet recording head toperform recording.

2. Related Background Art

Recording apparatuses such as printers, copying machines, facsimilesystems, and the like, which are used together with computers orwordprocessors, or are used individually , feed and convey sheet-likerecording media such as paper sheets or plastic thin plates, and recordimages on the recording media on the basis of image information. Therecording apparatuses can be classified into an ink jet system, awire-dot system, a thermal system, a laser beam system, and the likedepending on their recording systems.

Of these systems, the ink jet recording system (ink jet recordingapparatus) causes recording means (recording head) to discharge inktoward a recording medium to perform recording. The ink jet recordingsystem has the following advantages. That is, the system can record ahigh-quality image at high speed, and can perform recording on normalpaper without always requiring special treatment. Since the ink jetrecording system is a non-impact system, noise is low, and it is easy torecord a color image using many color inks. Of the ink jet recordingsystem, an ink jet recording apparatus employing a line-type recordingmeans in which a large number of discharge ports are aligned in thewidthwise direction of a paper sheet can attain recording operations ata higher speed.

In particular, in an ink jet recording means (recording head) which usesheat energy as energy for discharging ink, electrothermal transducerswhich are formed on a substrate via semiconductor manufacturingprocesses such as etching, deposition, sputtering, and the like, liquidpath walls, a top plate, and the like are formed, so that a recordinghead having a high-density liquid path arrangement (discharge portarrangement) can be easily manufactured.

Such an ink jet recording apparatus normally comprises an arrangementfor keeping a satisfactory ink discharging state by preventing anincrease in ink viscosity due to evaporation of an aqueous ink componentin discharge ports or a portion around them where a recording liquid(ink) contacts air, or by removing an ink whose viscosity is increased.

In particular, in a recording head of a type for discharging an ink byutilizing heat energy, since discharge ports and liquid pathscommunicating with the ports can be arranged very precisely at a highdensity, the influence of an increase in ink viscosity tends to berelatively increased.

For this reason, each of these ink jet recording apparatuses comprises acapping mechanism for covering and closing (capping) a surface wheredischarge ports of a recording head are arranged in a non-recordingoperation state during which no ink is discharged, thereby preventingevaporation of an aqueous ink component from the discharge ports. Inorder to assure stable ink discharge, ink is periodically dischargedfrom all or desired discharge ports of a recording head at apredetermined position during, e.g., a recording operation, thusperforming so-called preliminary discharge (idle discharge) for renewingan ink in particular discharge ports which are not involved inrecording. In addition, an ink absorbing recover or ink compressionrecover operation for discharging a viscosity-increased ink or a foreignmatter by absorbing or compressing an ink in the discharge ports at thebeginning of recording or at predetermined time intervals is performed.

However, for example, when capping of an ink jet recording head isperformed by executing a series of power-off sequences, a circuit foroperating an activating source such as a motor for a predeterminedperiod of time by, e.g., a relay is required, resulting in a complexapparatus arrangement. In addition, upon completion of a recordingoperation, a power source cannot be turned off until the power-offsequences are completed, resulting in an inconvenience. Furthermore, inthis case, attachment of a foreign matter or dust can be prevented bycapping the ink jet recording head. However, since an increase inviscosity of an ink in the ink jet recording head cannot besatisfactorily prevented, this may cause a discharge error including anink non-discharge state in the next recording operation.

When ink is forcibly discharged upon a power-on operation of the ink jetrecording apparatus, a fixed amount of ink is always discharged althoughthe degree of increase in viscosity of ink in the ink jet recording headvaries depending on the non-use time of the ink jet recording apparatus.For this reason, when a power source is frequently turned on/off, stepsagainst waste of an ink, an increase in running cost, contamination ofthe interior of the apparatus due to the discharged ink, and the likemust be taken.

Furthermore, since recover operations such as absorbing, compression,and idle discharge operations are added, time is wasted in addition toan original recording time, and as the result, a recording speed isundesirably lowered.

Moreover, when an ink jet recording apparatus is left for a long periodof time while its power source is kept OFF, or is left in alow-temperature condition, a discharge error (e.g., unstable dischargeor non-discharge state) may occur due to an increase in viscosity of anink or sticking of an ink in the ink discharge ports. As a method ofsolving this problem, sequences for performing recover operations of arecording means (recording head) upon a power-on operation areperformed, as described above. In the conventional power-on recoveroperations, an absorbing recover operation is constantly performedregardless of the environmental temperature of the recording means, orthe temperature around the recording means is detected only upon apower-on operation, and the number of times the absorbing recoveroperation is conducted is increased/decreased according to the detectedtemperature, thus changing a treatment level.

However, in the conventional recover method, judgment of an ink stickingstate in the discharge ports can only be made by a detected temperaturearound the recording means upon a power-on operation. For example, whenan abrupt change in temperature occurs immediately before use of therecording apparatus, or when the recording apparatus is left in alow-temperature state for a long period of time before the power sourceis turned on, it is impossible to correctly determine an ink stickingstate of the recording means (recording head). FIG. 25 is a graph forexemplifying a change in temperature when a temperature of the recordingmeans is abruptly increased immediately before the recording apparatusis used, and FIG. 26 is a graph for exemplifying a change in temperatureof the recording means when the apparatus is left in a low-temperaturestate for a long period of time before the power source is turned on. InFIGS. 25 and 26, a standard temperature corresponds to a temperature atwhich an ink sticking phenomenon begins below this temperature.

For these reasons, the conventional control method of recover operationsof the recording means cannot determine an ink sticking state upon apower-on operation due to a hysteresis temperature before the powersource is turned on. Therefore, since the recover operations upon apower-on operation cannot be performed according to an actual inksticking state, control becomes unsatisfactory. As a result, an inkdischarging state in recording becomes unstable, and recording qualitycannot be maintained. In order to guarantee stability of an inkdischarging state, recover operations must be excessively performed, andwaste of ink and time cannot be avoided.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an ink jet recordingapparatus which can efficiently perform a head recover operation bydischarging ink, and can maintain an ink jet recording head in a normalink discharging state.

It is another object of the present invention to provide an ink jetrecording apparatus which can control an ink amount consumed inpreliminary discharge within a necessary range, and can prevent waste ofink even when an ON/OFF operation of a power source of the recordingapparatus is repeated a large number of times (frequently) within ashort period of time.

It is still another object of the present invention to provide an inkjet recording apparatus which measures at least one of a time elapsedfrom a previous idle discharge operation, a time elapsed from a previousabsorbing operation, and a time of a capping state or an uncapping stateto appropriately select a treatment content of a recover operation, andcan eliminate waste of ink and a loss in recording time due to anunnecessary idle discharge or absorbing operation.

It is still another object of the present invention to provide an inkjet recording apparatus which can avoid an unnecessary dischargestabilization treatment on the basis of a hysteresis of the dischargestabilization treatment.

It is still another object of the present invention to provide an inkjet recording apparatus which can correctly judge an ink sticking stateupon a power-on operation to optimize a recover operation upon apower-on operation, thereby eliminating a recording error caused by adischarge error, and preventing waste of an ink and time caused by awasteful recover treatment upon a power-on operation.

It is still another object of the present invention to provide an inkjet recording apparatus comprising timer means for measuring an elapseof time from a predetermined measurement start timing, a backup powersource for supplying power to the timer means when a main power sourceis turned off, and control means for changing the content and/or thefrequency of a recover operation for recovering and preventing adischarge error in a discharge port for discharging an ink on the basisof the elapsed time.

The ink jet recording apparatus performs a head recover operation fordischarging ink from an ink jet recording head when a power source isturned on, thereby removing foreign matter, e.g., a viscosity-increasedink in the ink jet recording head, which causes discharge errorsincluding an ink non-discharge state. A non-use time in which norecording operation is performed, i.e., from a power-off operation untilthe next power-on operation is counted, and an ink discharge amount in ahead recover treatment can be set according to the counted non-use time.Therefore, when the non-use time is short, and ink viscosity is low, anink discharge amount is limited to suppress an ink consumption amount.On the other hand, when the non-use time is long and an ink viscosity ishigh, an ink discharge amount is increased to reliably remove theforeign matter.

Since a timer for counting the non-use time of the ink jet recordingapparatus is reset upon completion of the head recover operation, evenwhen the power source is turned off immediately after it is turned on,the timer will not be reset as long as the head recover operation is notcompleted, and counts the non-use time, i.e., a non-recording operationtime from a power-off operation upon completion of the previous headrecover operation. Therefore, when the power source is turned on for thenext time, the head recover operation can be performed in accordancewith an ink discharge amount according to the non-use time.

Furthermore, a number of discharge stabilization treatments includingidle discharge and ink absorbing operations is selected in accordancewith at least one of an elapse of time from the last ink discharge orink absorbing operation or an elapse of time in a capping state or anuncapping state. Since the elapsed time can be calculated even when thepower source of the ink jet recording apparatus is not turned on, adischarge state of the recording head during a non-use time of theapparatus can be administered.

In addition, a power-off control unit measures temperature near arecording means in a power-off state (e.g., measures the temperatureevery minutes during 30 minutes until a power-on operation), andcontrols the number of recover operations or an absorbing force upon apower-on operation in accordance with parameters indicating the numberof measurement values below a standard temperature, the number ofcontinuous measurement values below the standard temperature, and thelike, thus optimizing a recover operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an embodiment of an ink jetrecording apparatus according to the present invention;

FIG. 2 is a perspective view showing a recording head;

FIG. 3 is a block diagram showing the ink jet recording apparatus shownin FIG. 1;

FIG. 4 is a block diagram showing a controller;

FIGS. 5A and 5B are timings charts showing set and reset timings of atimer by the controller, respectively;

FIG. 6 is a flow chart showing an operation of the ink jet recordingapparatus according to the present invention;

FIG. 7 is a perspective view showing an ink jet recording apparatusaccording to another embodiment of the present invention;

FIG. 8 is a plan view showing in detail a cap and a tube pump shown inFIG. 7;

FIG. 9 is a block diagram showing an arrangement of a controller shownin FIG. 7;

FIG. 10 is a flow chart showing a processing sequence of thisembodiment;

FIG. 11 is a block diagram showing a modification of the controllershown in FIG. 9;

FIGS. 12A and 12B are respectively a block diagram and a timing chart ofa latch IC shown in FIG. 11;

FIG. 13 is a perspective view showing an arrangement of main part of anink jet recording apparatus according to still another embodiment of thepresent invention;

FIG. 14 is a partial perspective view showing a structure of a recordinghead shown in FIG. 13;

FIG. 15 is a block diagram showing an arrangement of a control system ofthe ink jet recording apparatus of this embodiment;

FIG. 16 is a flow chart showing a preliminary discharge sequence upon afirst power-on operation in the ink jet recording apparatus of thisembodiment;

FIG. 17 is a flow chart showing a preliminary discharge sequence upon asecond power-on operation in the embodiment shown in FIG. 16;

FIG. 18 is a flow chart showing a preliminary discharge sequence upon afirst power-on operation according to still another embodiment of an inkjet recording apparatus;

FIG. 19 is a flow chart showing a preliminary discharge sequence upon asecond power-on operation in the embodiment shown in FIG. 18;

FIG. 20 is a perspective view of an ink jet recording apparatusaccording to still another embodiment of the present invention;

FIG. 21 is a partial perspective view showing a structure of an inkdischarge unit of a recording means shown in FIG. 20;

FIG. 22 is a block diagram showing an arrangement of a control system ofthe ink jet recording apparatus of this embodiment;

FIG. 23 is a graph for exemplifying a temperature near the recordingmeans measured by the control system shown in FIG. 22 in a power-offstate of the recording apparatus;

FIG. 24 is a flow chart showing an operation of the control system shownin FIG. 22;

FIG. 25 is a graph showing a change in temperature near the recordingmeans in a power-off state in the ink jet recording apparatus; and

FIG. 26 is a graph showing another change in temperature near therecording means in a power-off state of the ink jet recording apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be described hereinafterwith reference to accompanying drawings.

In the ink jet recording apparatus of this embodiment, as shown in FIG.1, an ink jet head cartridge 1 integrating an ink jet recording head 3and an ink tank (not shown) is mounted on a carriage 2, and the carriage2 is coupled to a portion of an activating belt 4 for transmitting anactivating force of an actuating motor 5. The carriage 2 is slidablealong two parallel guide shafts 6a and 6b. The carriage 2 isreciprocally moved over the total width of a recording medium fed from amedium feeding device (not shown) to a platen 7 arranged to oppose adischarge surface of the ink jet recording head 3, so that the ink jetrecording head 3 performs recording on the recording medium.

As shown in the partial perspective view in FIG. 2, a plurality of inkdischarge ports 12 are juxtaposed on the discharge surface opposing therecording medium, and electrothermal transducers 13 for generatingenergy for discharging ink and applying it to communicating with thedischarge ports 12 are arranged in correspondence with the dischargeports 12.

The ink jet recording apparatus comprises a head recovering device 8comprising a cap member 8a for capping the discharge surface of the inkjet recording head 3. The head recovering device is activated by anactivating force of a cleaning motor 10 via a transmission mechanism 11at a position which falls outside a range of a reciprocal movement ofthe ink jet recording head 3 in a recording operation, and where the inkjet recording head is stopped in a non-recording mode (i.e., the leftend of the guide shaft 6a in FIG. 1; to be referred to as a "homeposition" hereinafter) when a head recover operation of the ink jetrecording head 3 is performed. The head recovering device 8 forces inkto be discharged from the discharge ports 12 by performing an inkabsorbing operation by an absorbing means as an ink supply means to anink path in association with the capping operation of the dischargesurface of the recording head 3 by the cap member 8a during the headrecover operation. Thus, the head recover operation is performed toremove a viscosity-increased ink in the recording head 3. In addition, acontroller (to be described later) drives the electrothermal transducers13 of the recording head 3 to perform preliminary discharge of the inkjet recording head 3 in association with capping of the dischargesurface of the recording head 3 by the cap member 8a, or drives theelectrothermal transducers 13 so as not to discharge ink, thusdecreasing viscosity of an ink in the ink path of the recording head 3.The head recover operation can also be performed in this manner.

Furthermore, a blade (wiping member) 9 formed of silicone rubber is heldby a blade holding member 9a on a side surface of the head recoveringdevice 8 in a cantilever manner, and is operated by the cleaning motor10 and a transmission mechanism 11 like in the head recovering device 8,thus allowing frictional engagement with the discharge surface of theink jet recording head 3. Thus, after the head recover operation usingthe head recovering device 8, the blade wiping member 9 projects intothe moving path of the ink jet recording head 3, and wipes dew, wettingink, dust, or the like on the discharge surface of the recording head 3upon movement of the ink jet recording head 3.

A control system of this embodiment will be described below withreference to FIG. 3.

FIG. 3 is a block diagram showing the ink jet recording apparatusdescribed above, and illustrates a state wherein the ink jet recordingapparatus is connected to a host device 20 as an external device.

When a power switch 37 is turned on, a power source voltage is appliedfrom a power device 38, and a controller 30 starts its operation. Inthis manner, the ink jet recording apparatus of this embodiment isstarted. When the power switch 37 is turned on, a power-on indication ismade on a panel 32. The panel 32 is one for operations, which comprisesa display means, and switches, e.g., a recording paper feed switch, andis connected to the controller 30. The display means can display anoperation mode, e.g., a recording operation mode, a head recoveroperation mode, and the like in addition to the power-on indication.

The recording operation and the head recover operation of the ink jetrecording apparatus are controlled by the controller 30. The controller30 is connected to a sensor 34 for a head activating system foractivating the electrothermal transducers 13 of the ink jet recordinghead 3, a sensor 35 for a mechanical activating system for activatingthe activating motor 5 and the cleaning motor 10, and an activatingcircuit 36 for the recovering device for activating an absorbing meansof the head recovering device 8. The controller 30 receives documentinformation from the host device 20 as an external device via aninterface circuit 33, and activates the electrothermal transducers 13 ofthe recording head 3 via the sensor 34, thus causing the recording head3 to discharge ink. The controller 30 is also connected to a timer 31which is set when the power switch 37 is turned off, and is reset uponcompletion of the head recover operation.

The arrangement of the controller 30 will be described below withreference to FIG. 4.

The controller 30 of this embodiment comprises an MPU 301, a ROM 302,and a comparing circuit 303. The MPU 301 performs control operationsassociated with the recording operation and the head recover operationin accordance with a program prestored in the ROM 302. In thisembodiment, it is determined by the program that the head recoveroperation is performed when the power switch of the ink jet recordingapparatus is turned on.

The MPU 301 sets a timer 31 when the power switch 37 of the ink jetrecording apparatus is turned off, and resets the timer 31 uponcompletion of the head recover operation. When the power switch of theink jet recording apparatus is turned on, the MPU 31 reads a countnumber of the timer 31 at that time, and transfers it to the comparingcircuit 303. Therefore, the count number of the timer 31 indicates anon-use time between an OFF operation of the power switch to the next ONoperation of the ink jet recording apparatus. Upon reception of thecount number of the timer 31 read by the MPU 301, the comparing circuit303 looks up a mode table 304 shown in Table 1 below and prestored inthe ROM 302 together with the program, selects an operation modesuitable for an elapse of time corresponding to the received countnumber, and transfers it to the MPU 301.

                  TABLE 1                                                         ______________________________________                                        Elapse Time      Recover Operation Mode                                       ______________________________________                                        Within 6 Hours   Preliminary Discharge (N.sub.1                                                Times)                                                       More Than 6 Hours to 3                                                                         Preliminary Discharge (N.sub.2                               Days             Times)                                                       More Than 3 Days to 10                                                                         Ink Heating + Preliminary                                    Days             Discharge (N.sub.3 Times)                                    More than 10 Days to 1                                                                         Ink Absorbing (N.sub.4 Times)                                Month                                                                         More than 1 Month to 6                                                                         Ink Absorbing (N.sub.5 Times)                                Months                                                                        More than 6 Months                                                                             Ink Absorbing (N.sub.6 Times) +                                               Test Pattern Printing                                        ______________________________________                                    

The above-mentioned mode table 304 defines the recover operation modesto be executed in correspondence with the elapsed times in the headrecover operation. The recover operation modes include a preliminarydischarge mode, an ink heating mode, an ink absorbing mode, a testpattern printing mode, and combinations thereof, as shown in Table 1.

When the recover operation mode selected by the comparing circuit 303 isthe preliminary discharge mode, the MPU 301 activates the cleaning motor10 via the sensor 35 to cause the cap member 8a of the head recoveringdevice 8 to cap the discharge surface of the ink jet recording head 3.In this state, the MPU 301 activates the electrothermal transducers 13of the recording head 3 via the sensor 34 to cause them to perform anink discharge operation a predetermined number of times. When theselected recover operation mode is a combination of the ink heatingmode+the preliminary discharge mode, the MPU 301 activates theelectrothermal transducers 13 via the sensor 34 for a predeterminedperiod of time so as not to discharge ink, thereby heating the ink todecrease ink viscosity. Thereafter, the ink discharge operation isperformed like in the preliminary discharge mode. When the selectedrecover operation mode is the ink absorbing mode, the MPU 301 activatesthe absorbing means in the head recovering device 8 via the activatingcircuit 36 in a state wherein the discharge surface of the recordinghead 3 is capped as described above. Thus, the ink absorbing operationis performed at a predetermined absorbing pressure a predeterminednumber of times, thereby forcibly discharging ink from the dischargeports 12. When the selected recover operation mode is a combination ofthe ink absorbing mode plus the test pattern printing mode, the forcedink discharge operation of the recording head 3 is performed asdescribed above. Thereafter, the cap member 8a is uncapped from therecording head 3, and the electrothermal transducers 13 of the recordinghead 3 are activated according to printing data representing apredetermined test pattern, thereby printing the test pattern on arecording medium.

Set and reset timings of the timer 31 by the MPU 301 will be describedbelow with reference to FIGS. 5A and 5B.

As shown in FIG. 5A, when the power switch 37 of the ink jet recordingapparatus is turned off at time t₁, supply of the power source voltagefrom the power device 38 is stopped, and a logic voltage as an operationvoltage of the controller 30 begins to fall. When the logic voltagereaches a threshold level V_(TH) of the operation voltage of thecontroller 30 at time t₂, the operation of the controller 30 is stopped,and the timer 31 is set, thus starting a count operation of the timer31. Thereafter, when the power switch 37 of the ink jet recordingapparatus is turned on again at time t₃, the logic voltage begins torise. When the logic voltage reaches the threshold level V_(TH) gat timet₄, the controller 30 is started, and the head recover operation isexecuted. When the head recover operation is completed at time t₅, thetimer 31 is reset by a signal indicating completion of the head recoveroperation issued by the MPU 301 at that time.

When the power switch 37 is successively turned on/off, and is turnedoff at time t₆ in the middle of the head recover operation, as shown inFIG. 5B, since no signal indicating completion of the head recoveroperation is output from the MPU 301, the timer 31 is not reset, andkeeps counting an elapse of time from the OFF operation of the powerswitch 37 at time t₁ described above.

The operation of this embodiment will be described below with referenceto the flow chart shown in FIG. 6.

When the recording operation of the ink jet recording apparatus iscompleted, and the power switch 37 is turned off, supply of the powersource voltage from the power device 38 is stopped, and the operation ofthe controller 30 is stopped. At the same time, the timer 31 is set(step S501). Thereafter, the timer 31 counts an elapse of time from thepower-off operation by the power switch 37.

When the power switch 37 of the ink jet recording apparatus is turned onagain, and the controller 30 is started, the MPU 301 of the controller30 reads a count number of the timer 31 at that time (step S502). Thecomparing circuit 303 of the controller 30 sequentially looks up themode table 304 on the basis of the read count number, selects a recoveroperation mode suitable for the elapse of time corresponding to thecount number (steps S503 to S507), and transfers it to the MPU 301. Ifthe read count number indicates, e.g., four days, "ink heating mode pluspreliminary discharge mode (N₃ times)" in step S510 is selected. In thiscase, in the controller 30, the MPU 301 activates the sensors 34 and 35to execute the ink heating operation, and then to execute thepreliminary discharge operation N₃ times. Upon completion of theseoperations, the MPU 301 outputs a signal indicating completion of thehead recover operation, thereby resetting the timer 31 (step S514). Inthis manner, the head recover operation upon a power-on operation of theink jet recording apparatus is completed, and the recording operationcan be started.

In this embodiment, when the ink absorbing operation is performed usingthe ink absorbing means in the head recover operation, the number ofabsorbing operations for absorbing ink at a predetermined absorbingpressure is changed in accordance with an elapse of time from the OFFoperation of the power switch. Alternatively, an absorbing pressure maybe changed while the number of absorbing operations is kept constant.

In place of the absorbing means, compression means for compressing anink in the ink path of the head may be arranged as the head recoveringdevice. In this case, the number of compression operations or acompression force is changed in accordance with the elapsed time, thusobtaining the same effect as described above.

As described above, the timer is set when the power switch of the inkjet recording apparatus is turned off, and a count number of the timeris read when the power switch of the ink jet recording apparatus isturned on, thus obtaining a non-use time of the ink jet recordingapparatus. Furthermore, since an ink discharge amount from the ink jetrecording head in the head recovering operation is determined incorrespondence with the non-use time, even when the power switch isfrequently turned on/off, waste of ink can be avoided, andhigh-viscosity ink can be reliably removed even when an increase inviscosity of an ink in the ink jet recording head is considerable.

Since the head recover operation is performed when the power switch ofthe ink jet recording apparatus is turned on, a foreign matter forcausing an ink non-discharge state can be reliably removed from the inkjet recording head before a recording operation is started. As a result,image recording precision can be increased, and reliability of therecording apparatus can be improved.

Furthermore, even when the power switch of the ink jet recordingapparatus is turned off immediately after it is turned on, the timerwill not be reset and keeps counting as long as the head recoveroperation is not completed. Therefore, a non-use time of the ink jetrecording apparatus, in which no recording operation is performed, canbe precisely obtained.

Another embodiment of the present invention will be described below withreference to the accompanying drawings.

FIG. 7 is a perspective view of an ink jet recording apparatus accordingto another preferred embodiment of the present invention.

The ink jet recording apparatus shown in FIG. 7 comprises recording headcartridges 101C, 101M, and 101Y, and colors of ink discharged from thesecartridges correspond to C (cyan), M (magenta), and Y (yellow) in theorder named. Each of the head cartridges 101C, 101M, and 101Y isintegrally formed by an ink tank for storing a corresponding ink, and arecording head for discharging the ink. The head cartridges 101C, 101M,and 101Y are fixed on a carriage 115 by pressing members 141, and thecarriage 115 is reciprocally movable along the longitudinal direction ofshafts 121. Ink discharged from discharge ports of the recording headsreaches a recording medium 118 whose recording surface is regulated by aplaten 119 arranged to be separated from the discharge ports at a smallinterval, thus forming an image on the recording medium 118.

A discharge signal according to recording data supplied via a cable 116is applied to electrothermal transducers (for generating heat energy)arranged in the recording heads and serving as discharge energygeneration elements for generating energy utilized to discharge ink.

The ink jet recording apparatus also comprises a carriage motor 117 forreciprocally moving the carriage 115 along the shafts 121, and a wire122 for transmitting an activating force of the motor 117 to thecarriage 115. A feed motor 120 rotates the platen roller 119 via a geartrain. Thus, the platen roller 119 conveys the recording medium 118upward in the apparatus.

The apparatus also comprises a wiping blade 105 which partially projectsinto a moving path adjacent to a recording moving path of the movingpath of the head cartridges 101C, 101M, and 101Y. The blade 105relatively slides along the discharge port surfaces of the recordingheads upon reciprocal movement of the head cartridges 101C, 101M, and101Y to capping positions (to be described later), thereby removing inkor dust attached to the discharge port surfaces. Thus, deflection of adischarge direction of ink droplets discharged from the discharge portsand sticking of the discharge ports due to dried ink can be prevented.

Caps 102C, 102M, and 102Y are arranged along the end portion of themoving path of the head cartridges 101C, 101M, and 101Y incorrespondence with these cartridges. The caps 102C, 102M, and 102Y arerespectively held by cap holders 102CH, 102MH, and 102YH (not shown inFIG. 7). These cap holders are movable in a direction perpendicular tothe moving path of the head cartridges. Note that a moving mechanism forthe cap holders is not shown. A tube pump 142 forcibly absorbs ink fromthe interiors of the discharge ports of the recording heads via the caps102C, 102M, and 102Y, and will be described in detail later withreference to FIG. 8.

Idle discharge, ink absorbing, and capping operations are performed atthe capping positions where these caps 102C, 102M, and 102Y arearranged.

More specifically, in the idle discharge operation, an ink dischargeoperation is performed a desired number of times toward ink receivingmembers arranged on the front surface of the respective caps. Thus, inknear the discharge ports which is not frequently discharged is renewed,and viscosity-increased ink is discharged, thereby attaining uniformdischarge characteristics among the discharge ports.

In the ink absorbing operation, the caps 102C, 102M, and 102Y are movedto close the discharge port surfaces of the recording heads, and in thisstate, ink in the discharge ports is absorbed by the tube pump 142. Withthis operation, viscosity-increased ink and solidified ink around andinside the discharge ports, which are caused by a relatively longnon-recording time, can be discharged. In the capping operation, thedischarge port surfaces are simply covered by the caps. Thus, ink nearthe discharge ports can be prevented from drying in a non-recordingstate.

As can be seen from the above description, the ink absorbing operationhas a larger discharge recover effect than that of the idle dischargeoperation, and ink consumption amount is increased accordingly.

FIG. 8 is a plan view showing in detail the capping and ink absorbingmechanisms. The caps 102C, 102M, and 102Y are formed of flexible memberssuch as rubber. In a capping mode, the cap holders 102CH, 102MH, and102YH are moved toward the recording heads by a moving means (notshown), and the caps are pressed against the corresponding dischargeport surfaces. Thus, the caps 102C, 102M, and 102Y properly close spacesnear the discharge ports.

Recess portions of the caps 102C, 102M, and 102Y communicate with adrain ink absorbing member 143 via a tube, and the tube pump 142 isengaged therebetween. The tube pump 142 comprises a guide roller 140rotated by an activating means (not shown) such as a motor, acompression roller 141 arranged on a portion of the guide roller, and atube guide 144 for regulating the position of the tube. The compressionroller 141 compresses the tube while sequentially changing its positionby rotating in a counter-clockwise direction about the guide roller 140,thereby forming a negative pressure in the recess portions of the caps102C, 102M, and 102Y, and conveying absorbed ink in a direction of thedrain ink absorbing member.

In FIG. 9 in a block diagram showing a control arrangement of the inkjet recording apparatus shown in FIG. 7, the apparatus comprises a CPU130 serving as a control unit for executing control processingassociated with the processing operations of the entire apparatus, and acapping position sensor 133 for detecting the above-mentioned cappingpositions. The sensor 133 detects the movement of members having a fixedpositional relationship with the caps, e.g., the cap holders. A timer IC132 outputs a signal serving as a reference for time. A memory 131 hasan area for storing time based on the signal output from the timer IC.For example, the CPU 130 resets the time data stored in the memory 131on the basis of a detection signal from the sensor 133 or processingexecuted by itself. More specifically, the memory 131 stores a cappingtime of the discharge port surfaces of the head cartridges, and a timeelapsed from the latest discharge operation. The memory 131 and thetimer IC 132 are backed up by a power source different from that of theapparatus of this embodiment, and can count, e.g., the capping timewhile the power source of the apparatus is kept OFF.

A recording head driver circuit 134 activates or drives the recordinghead cartridges 101C, 101M, and 10Y on the basis of recording data froma host device, and a control signal from the CPU 130, thereby performingan ink discharge operation. A motor driver circuit 136 drives the guideroller 140 of the tube pump 142 on the basis of a control signal fromthe CPU 130.

FIG. 10 is a flow chart showing a processing sequence according to thisembodiment. This processing is started automatically when the powersource is turned on, or in response to an input instructing thisprocessing by a user.

A head state holding operation to be described below means a dischargestabilization treatment including one of the capping, idle discharge,and ink absorbing (or compression) operations, or a combination thereof.

When this processing is started, data in the area of the memory 131 forstoring, e.g., a capping time is read in step S1. The data stored inthis area includes an elapse of time of a state wherein the heads arecapped, and an elapse of time from the latest discharge operation of therecording heads (from the end of the latest discharge operation).

It is checked in step S2 if the heads are presently capped. If YES instep S2, the flow advances to step S3, and the head state holdingoperation to be performed is branched in accordance with the elapse oftime in the capping state, which is read out in step S1. Morespecifically, if the elapse of time of the capping state falls within apredetermined time period (e.g., 1 hour), a holding operation 1 forperforming only an idle discharge operation is performed in step S5. Ifthe elapse of time of the capping state falls within anotherpredetermined time period (e.g., more than 1 hour and less than 24hours), a holding operation 2 for performing an ink absorbing operationonce, and the idle discharge operation is performed in step S6. If theelapse of time of the capping state exceeds the predetermined timeperiod (e.g., 24 hours), a holding operation 3 for performing the inkabsorbing operation twice and the idle discharge operation is performedin step S7.

If NO in step S2, i.e., if it is determined that the heads are notcapped, the flow advances to step S4, a holding operation is determinedin accordance with an elapse time from the latest discharge operation bythe recording heads. More specifically, if the recording heads are leftunoperated within for less than 24 hours from the latest dischargeoperation, a holding operation 4 for performing the ink absorbingoperation three times, and the idle discharge operation is performed instep S8. If the recording heads are unoperated for more than 24 hours, aholding operation 5 for performing the ink absorbing operation fivetimes, and the idle discharge is performed in step S9.

The number of ink absorbing operations in the holding operations are notlimited to those described above, and contents of the holding operationsare not limited to the combinations described above. More specifically,as the contents of the holding operations, contents capable ofminimizing ink consumption and time required for the correspondingholding operations, and capable of obtaining a satisfactory dischargerecover effect should be appropriately determined in independentapparatuses. Therefore, the elapse periods are not limited to thosedescribed above, and may be arbitrarily set in accordance withcharacteristics of ink jet heads and apparatuses.

The elapsed times as references for branching the respective stateholding operations are not limited to those described above. As will bedescribed later with reference to FIG. 11 and FIGS. 12A and 12B, anelapse of time of an uncapping state may also be used, and an elapse oftime from the latest absorbing operation may be used.

FIG. 11 is a block diagram showing a modification of the controlarrangement shown in FIG. 9.

The difference from the arrangement shown in FIG. 9 is that the cappingposition sensor is backed up by a power source different from that ofthe apparatus. Thus, even when the recording head cartridges aredisplaced from their capping positions due to paper jam removingprocessing or a recording head chip exchange operation while the powersource of the apparatus is kept OFF, a time during this interval can becounted, and processing shown in FIG. 10 can be more accuratelyexecuted.

FIGS. 12A and 12B are respectively a block diagram showing in detail alatch IC 150 arranged in a memory and its peripheral circuit 138 shownin FIG. 11, and a timing chart of signals.

An output B from the timer IC 132 becomes a data input of the latch IC150, and this input is gated by an output A from the sensor 133. As aresult, as shown in FIG. 12B, time Dn+₃ at which the heads are uncappedis latched, and is held. Thereafter, latched data is updated when theheads are capped again.

In this manner, a content of a discharge recover treatment consisting ofidle discharge and ink discharge operations is selected in accordancewith at least one of an elapse of time from the latest ink discharge orink absorbing operation, and an elapse of time of a capping or uncappingstate. The elapse of time can be held even when the power source of theink jet recording apparatus is kept OFF. Therefore, a discharge state ofthe recording head in a non-use time of the apparatus can beadministered.

As a result, an optimal recover treatment consisting of the inkabsorbing and idle discharge operations can be performed. Thus,unnecessary ink consumption by the recover treatment can be reduced, anda decrease in recording speed can also be prevented.

Still another embodiment of the present invention will be describedbelow with reference to the accompanying drawings.

In FIG. 13 as a perspective view showing a main part of an ink jetrecording apparatus according to still another embodiment of the presentinvention having a head unit 201 mounted on a carriage 203, and aplurality of (four in FIG. 13) recording heads 202A, 202B, 202C, and202D.

Discharge ports (normally, a plurality of ports) are formed on thedischarge port surfaces of the recording heads 202A to 202D, and therecording heads 202A to 202D discharge ink of different colors. Forexample, in a color ink jet recording apparatus, the recording heads202A to 202D can correspond to ink colors of, e.g., yellow, magenta,cyan, and black.

Each of the recording heads 202A to 202D is an ink jet recording headfor discharging ink by utilizing heat energy, and compriseselectrothermal transducers for generating heat energy. Each of therecording heads 202A to 202D discharges ink from the discharge ports bygrowth of bubbles by film boiling caused by heat energy applied from theelectrothermal transducers, thus performing recording.

In a block diagram of a control system shown in FIG. 15, the carriage203 which carries the head unit 201 is movably supported along guiderails 204, and is reciprocally driven by a carriage motor 206 via atiming belt 205.

A sheet-like recording medium 207 such as a paper sheet, a plastic thinplate, or the like is conveyed (fed) in a direction of an arrow f at apredetermined timing and a predetermined pitch along a predeterminedpath by a pair of convey rollers 209 driven by a convey motor (sheetfeed motor) 208, and a pair of holding rollers 210 which are interlockedwith the rollers 209. While the recording medium 207 is held flat at arecording position opposing the recording heads 202A to 202D, arecording operation is performed by main-scanning the recording heads202A to 202D. Upon completion of the recording operation for one line,the recording medium 207 is fed by a predetermined pitch in thedirection of the arrow f, and a recording operation for the next line isperformed.

Note that ink tanks 213A to 213D for supplying ink of correspondingcolors to the recording heads 202A to 202D are exchangeably mounted onthe carriage 203.

A home position H is set at a predetermined position within a movingrange of the carriage 203 and outside a recording region. A recoveringdevice 214 for recovering discharge errors including an inknon-discharge state of the recording heads 202A to 202D is arranged atthe home position H. The recovering device 214 has a cap 215 capable ofclosing the discharge port surfaces (surfaces where the discharge portsare formed) of the recording heads 202A to 202D.

FIG. 14 is a partial perspective view of an ink discharge portion of therecording head 202 (an arbitrary one of the recording heads 202A to202D) in FIG. 13. In FIG. 14, a plurality of discharge ports are formedon a discharge port surface 216 opposing the recording medium 207 at apredetermined gap (e.g., about 0.5 mm) at a predetermined pitch in thelongitudinal direction, and electrothermal transducers (having heatingresistors) 220 as heaters for discharging ink are arranged along wallsurfaces of liquid paths 219 for causing a common liquid chamber 218 tocommunicate with discharge ports 217.

Desired heaters 220 are driven (energized) on the basis of an imagesignal (recording information) to generate bubbles in the ink in theliquid paths 219. Flying ink droplets are formed based on the bubbles,and the ink droplets (dots) become attached to the recording medium 207,thus recording an image. When a power switch is turned on, and in othernecessary states, the recording heads 202A to 202D are moved to theposition of the cap 215, and the heaters (normally, heaters of all thedischarge ports) 220 are driven, thereby performing a preliminarydischarge operation for discharging ink from the discharge ports 217into the cap 215.

The preliminary discharge operation outside the recording region ismainly performed to eliminate discharge errors caused by sticking ink, aviscosity-increased ink, dust such as paper pieces, or bubbles in theink in the ink discharge portion (e.g., in the discharge ports 217 andthe liquid paths 219) of the recording head 202.

In FIG. 15 as a block diagram showing an arrangement of the controlsystem of the ink jet recording apparatus shown in FIG. 13, the heaters220 of the recording head 202 are driven by a driver 221, and electricalpower is supplied from a power source 222 to the driver 221 via avoltage changing circuit 223. An MPU 230 is connected to a timer 231,and can perform timer administration of the preliminary dischargeoperation.

In FIG. 15, the apparatus includes an I/O port 232 for receiving signalsfrom a host device, a ROM 233 for storing, e.g., a control program, acharacter generator 234, and a RAM 235 for storing, e.g., image signals.The carriage motor 206 and the convey motor 208 are controlled by theMPU 230 via an I/O port 237.

Furthermore, the MPU 230 receives, via the I/O port 237, detectionsignals from sensors 238 for detecting the presence/absence of therecording medium 207, the presence/absence of an ink remaining amount,whether or not the carriage 203 is located at the home position H, thepresence/absence of the ink cartridge (ink tank) 213, and the like.

In the ink jet recording apparatus for performing recording on therecording medium 207 by injecting ink from the recording heads 202, evenwhen a predetermined time is selected in timer administration in therecording apparatus, and the number of ON times of the power source ofthe recording apparatus is large, in the setting time, a preliminarydischarge operation for recovering discharge of the recording heads 202is performed only a small number of times. In this case, the settingtime can be set to be about 30 minutes, and the number of preliminarydischarge operations in the setting time can be set to be one or two.

Furthermore, in the ink jet recording apparatus for discharging ink fromthe recording heads 202 to perform recording on the recording medium 207according to this embodiment, a predetermined time is selected in timeradministration in the recording apparatus, and the number of preliminarydischarge activating pulses for recovering discharge of the recordingheads 202 is decreased as the number of ON times of the power source ofthe recording apparatus is increased. In this case, the number ofpreliminary discharge activating pulses can be controlled to besequentially decreased from an initial pulse count every time the powersource is turned on.

FIGS. 16 and 17 are flow charts of the preliminary discharge operationexecuted when the power source of the ink jet recording apparatus ofthis embodiment is turned on. FIG. 16 shows a sequence upon a firstpower-on operation, and FIG. 17 shows a sequence upon a second power-onoperation. In this embodiment, the number of preliminary dischargeoperations is controlled to be decreased to a smaller number of times(including zero) in accordance with the number of ON times of the powersource in a setting time.

In FIG. 16, after the power source is turned on for the first time instep S201, for example, a setting time n=30 minutes is set in the timer231, and the number of ON times of the power source=1 is stored in stepS202. In this case, since the power source is turned on beforerecording, the recording heads 202 are stopped at positions facing thecap 215 outside a recording region.

In step S203, the driver 221 is energized to activate the recordingheads 202 (to heat ink), and in step S204, a preliminary dischargeoperation is performed into the cap 215.

In step S205, it is checked if the power source is kept ON. If Y (YES)in step S205, the flow advances to step S206 to check if the timer 231reaches near an end of the setting time (a range of 30 minutes±1 minuteof an elapsed time in this embodiment). On the other hand, if N (NO) instep S205, the flow advances to step S207, and the time n and the numberof times m of ON times of the power source are sequentially stored inthe timer 231 until the timer 231 reaches the setting time.

In step S207, an elapsed time to be stored is indicated by x, and sincethe number of ON times of the power source is 1, m=1 is stored. If Y instep S206, the preliminary discharge operation is performed once againin step S208, and the flow advances to step S209. Thus, the controlenters a recording condition.

In this embodiment, since the number of preliminary discharge operationsin the setting time is set to be 2, the second preliminary dischargeoperation is performed in step S208. However, if the number ofpreliminary discharge operations in the setting time is set to be 1, thepreliminary discharge operation in step S208 is omitted. If the numberof preliminary discharge operations in the setting time is set to be 3or more, the preliminary discharge operation is performed in step S208 anumber of times obtained by subtracting 1 from the setup number oftimes. If the power source is kept ON, and if it is determined in stepS206 that the timer 231 has not reached the end of the setting time, theflow advances to step S209, and the control enters a recordingcondition.

If the second ON operation of the power source is detected after thefirst ON operation of the power source, an operation sequence shown inFIG. 17 is started. More specifically, after the power source is turnedon for the second time in step S210, it is checked in step S211 if thetimer 231 exceeds the setting time (30 minutes) in FIG. 16, and if thenumber of ON times m of the power source=2.

If-the setting time (setting time n in step S202, i.e., 30 minutes) isnot exceeded (within the setting time), the head driver 221 is turnedoff in step S212, and it is checked in step S213 if the power source iskept ON. If N in step S213, the flow advances to step S214, and the timen and the number of ON times m of the power source are sequentiallystored in the timer 231 until the timer 231 reaches the setting time. Instep S214, an elapse time is given by n=x+α, and the number of ON timesof the power source is m=3.

If it is determined in step S211 that the timer exceeds the setting time(30 minutes), the same operations as in steps S203 to S209 upon thefirst power-on operation in FIG. 16 are repeated. More specifically, instep S215, the driver 221 is energized to activate the recording heads202 (to heat an ink), and in step S216, ink is discharged into the cap215 (preliminary discharge operation). In step S217, it is checked ifthe power source is kept ON. If Y in step S217, the flow advances tostep S218 to check if the timer 231 has reached near the end of thesetting time (a range of 30 minutes±1 minute of an elapsed time in thisembodiment).

On the other hand, if N in step S217, the flow advances to step S219,and the time n and the number of times m of ON times of the power sourceare sequentially stored in the timer 231 until the timer 231 reaches thesetting time. In step S219, an of time to be stored is indicated by x,and the number m of ON times is stored as 1 since the setting time isexceeded. If it is determined in step S218 that the timer 231 hasreached near the end of the setting time (30 minutes±1 minute), thepreliminary discharge operation is performed once again in step S220,and the flow advances to step S221. Thus, the control enters a recordingcondition.

In this embodiment, since the number of preliminary discharge operationsin the setting time is set to be 2, the second preliminary dischargeoperation is performed in step S220. However, if the number ofpreliminary discharge operations in the setting time is set to be 1, thepreliminary discharge operation in step S220 is omitted. If the numberof preliminary discharge operations in the setting time is set to be 3or more, the preliminary discharge operation is performed in step S220 anumber of times obtained by subtracting 1 from the setup number oftimes.

If the power source is kept ON, and if it is determined in step S218that the timer 231 has not reached near the end of the setting time, theflow advances to step S221, and the control enters a recordingcondition.

If it is determined in step S213 that the power source is kept ON, theflow advances to step S218 to check if the timer 231 has reached nearthe end of the setting time (a range of 30 minutes±1 minute of an elapsetime in this embodiment). If Y in step S218, the preliminary dischargeoperation is executed once again in step S220 like in theabove-mentioned sequence, and thereafter, the control enters therecording condition in step S221; if N in step S218, the flow directlyadvances to step S221, and the control enters the recording condition.Thereafter, if the third and subsequent ON operations of the powersource are detected, the same operations as upon the second power-onoperation described above are repeated.

FIGS. 18 and 19 are flow charts of a preliminary discharge operation ofan ink jet recording apparatus upon a power-operation according toanother embodiment. FIG. 18 shows a sequence upon a first power-onoperation, and FIG. 19 shows a sequence upon a second power-onoperation. In this embodiment, the number Z of preliminary dischargeactivating pulses upon a power-on operation is controlled.

In FIG. 18, after the power source is turned on for the first time instep S101, for example, a setting time n=30 minutes is set in the timer231, and the number of ON times of the power source=1 is stored in stepS102. In this case, since the power source is turned On beforerecording, the recording heads 202 are stopped at positions facing thecap 215 outside a recording region.

In step S103, the frequency of the head driver 221 is controlled, and instep S104, the recording heads 202 are activated (i.e., the heaters 220are energized) a number of times corresponding to the frequency (numberof pulses), and the preliminary discharge operation is performed by thesetting number of activating pulses. In this case, the initial number ofactivating pulses is set to be, e.g., y=30 Hz. Since the number of ONtimes m of the power source is 1, an ink droplet discharge operation ofy/m=30 times (Hz) is set.

It is then checked in step S105 if the power source is kept ON.

If Y in step S105, the flow advances to step S106 to check if the timer231 has reached near the end of the setting time (a range of 30minutes±1 minute of an elapsed time in this embodiment), and to confirmif the power source is turned on for the second time.

If N in step S105, the flow advances to step S107, and the time n andthe number of times m of ON times of the power source are sequentiallystored in the timer 231 until the timer 231 reaches the setting time. Instep S107, an elapsed time to be stored is indicated by x, and since thenumber of ON times of the power source is 1, m=1 is stored.

If it is determined in step S106 that the timer 231 has reached near theend of the setting time (30 minutes±1 minute), the flow advances to stepS108 to perform frequency control of the head driver 221. In this case,since the number of ON times m of the power source is 2, the number ofpreliminary discharge activating pulses of the recording heads 202 isset to be y/m=30/2=15 pulses (times).

In step S109, the preliminary discharge operation is performed onceagain by this setting number of pulses (15 times). Thereafter, the flowadvances to step S110, and the control enters a recording condition.

In this embodiment, the number of preliminary discharge activatingpulses within the setting time is sequentially decreased in accordancewith the number of ON times of the power source.

If the power source is kept ON, and if it is determined in step S106that the timer 231 has reached near the end of the setting time, theflow advances to step S110, and the control enters the recordingcondition.

If the second ON operation of the power source is detected after thefirst ON operation of the power source, an operation sequence shown inFIG. 19 is started. More specifically, after the power source is turnedon for the second time in step S111, it is checked in step S112 if thetimer 231 exceeds the setting time n=30 minutes set upon the firstpower-on operation, and if the number of ON times m of the power sourceis 2.

If it is determined that the timer does not exceed the setting time(within the setting time), the head driver 221 is turned off in stepS113, and it is checked in step S114 if the power source is kept ON. IfY in step S114, the flow advances to step S115, and the time n and thenumber of times m of ON times of the power source are sequentiallystored in the timer 231 until the timer 231 reaches the setting time.

In step S115, an elapsed time n=x+α, and the number of ON times m=3 ofthe power source are stored.

If it is determined in step S112 that the timer exceeds the setting time(30 minutes), substantially the same operations as in steps S103 to S109upon the first power-on operation in FIG. 18 are performed, except thatthe number of ON times m of the power source is larger by one, andhence, the frequencies in steps S103 and S108 are decreased accordinglyto execute the preliminary operations by the smaller number ofactivating pulses.

More specifically, the frequency of the head driver 221 is controlled instep S116, and the recording heads 202 are activated (the heaters 220are energized) a number of times corresponding to the frequency (numberof pulses) in step S117, thus performing the preliminary dischargeoperation by the setting number of activating pulses. In this case, theinitial number of activating pulses is set to be y=30 Hz, and since thenumber of ON times m of the power source is 2, an ink droplet dischargeoperation of y/m =30/2=15 times (Hz) is set, thus performing thepreliminary discharge operation.

It is then checked in step S118 if the power source is kept ON.

If Y in step S118, the flow advances to step S119 to check if the timer231 has reached near an end of the setting time (a range of 30 minutes±1minute of an elapse time in this embodiment), and to confirm if thepower source is turned on for the third time.

If N in step S118, the flow advances to step S120, and the time n andthe number of times m of ON times of the power source are sequentiallystored in the timer 231 until the timer 231 reaches the setting time. Instep S120, an elapsed time x and the number of ON times m=1 of the powersource are stored.

If it is determined in step S119 that the timer 31 has reached near theend of the setting time (30 minutes±1 minute), the flow advances to stepS121 to perform frequency control of the head driver 221. In this case,since the number of ON times m of the power source is 3, the number ofpreliminary discharge activating pulses of the recording heads 202 isset to be y/m=30/3=10 pulses (times).

In step S122, the preliminary discharge operation is performed onceagain by this setting number of pulses (10 times). Thereafter, the flowadvances to step S123, and the control enters the recording condition.

If the power source is kept ON, and if it is determined in step S119that the timer 231 has reached near the end of the setting time, theflow advances to step S123, and the control enters the recordingcondition.

If it is determined in step S114 that the power source is kept ON, thefrequency of the head driver 221 is controlled in step S124, and therecording heads 202 are activated (the heaters 220 are energized) anumber of times corresponding to the frequency (number of pulses) instep S125, thus executing the preliminary discharge operation by thesetting number of activating pulses. In this case, the initial number ofactivating pulses is set to be y=30 Hz, and since the number of ON timesm of the power source is 2 in step S124, an ink droplet dischargeoperation of y/m=30/2=15 times (Hz) is set. In step S125, thepreliminary discharge operation is performed 15 times (for 15 pulses).

After the preliminary discharge operations in steps S124 and S125 areperformed, the flow advances to step S119 described above, and the sameoperation as described above is performed.

In this manner, in the second power-on sequence (FIG. 19), if thisoperation is performed within the setting time, the preliminarydischarge operation is performed by a smaller number of activatingpulses than that upon the first power-on operation (FIG. 18).

Thereafter, if the third and subsequent power-on operations areperformed within the setting time, the preliminary discharge operationsare performed by the numbers of pulses which are decreased in accordancewith an increase in the number of ON times m of the power source in thesame sequence as that upon the second power-on operation (FIG. 19).

According to the embodiment described above, when the power source isrepetitively turned on within a predetermined period of time, necessarypreliminary discharge operations can be performed without performingunnecessary preliminary discharge operations. Therefore, an ink jetrecording apparatus which can suppress wasteful ink discharge (inkconsumption) can be obtained.

In the above embodiment, the present invention is applied to aserial-scan type ink jet recording apparatus in which the recordingheads 202 are mounted on the carriage 203. However, the presentinvention can be similarly applied to other ink jet recordingapparatuses, e.g., an ink jet recording apparatus which employs a linetype recording head which can cover a recording region in the widthwisedirection of a recording medium, and the same effects as described abovecan be attained.

In the above embodiment, a color ink jet recording apparatus using thefour recording heads 202 has been exemplified. However, the presentinvention can be applied to a monochrome recording ink jet recordingapparatus using a single recording head, a gradation recording ink jetrecording head using a plurality of recording heads having the samecolor but different densities, and the like, regardless of the number ofrecording heads, and the same effects as described above can beattained.

As can be seen from the above description, in an ink jet recordingapparatus for discharging an ink from recording heads to performrecording on a recording medium, a predetermined time is set in timeradministration in the recording apparatus, and even when the number ofON times of the power source of the recording apparatus is large,preliminary discharge operations for recovering discharge of therecording heads are performed a small number of times within the settingtime. Therefore, when the power source of the recording apparatus isrepetitively turned on a large number of times (frequently), the inkamount consumed by the preliminary discharge operations can becontrolled to fall within a necessary range. As a result, an ink jetrecording apparatus which can eliminate wasteful consumption of an inkcan be provided.

In an ink jet recording apparatus for discharging the ink from recordingheads to perform recording on a recording medium, a predetermined timeis set in timer administration in the recording apparatus, and thenumber of activating pulses for preliminary discharge operations forrecovering discharge of the recording heads is decreased in accordancewith an increase in the number of ON times of the power source of therecording apparatus within the setting time. Therefore, when the powersource of the recording apparatus is repetitively turned on a largenumber of times (frequently), the ink amount consumed by the preliminarydischarge operations can be controlled to fall within a necessary range.As a result, an ink jet recording apparatus which can eliminate wastefulconsumption of an ink can be provided.

Still another embodiment of the present invention will be describedbelow with reference to the accompanying drawings. FIG. 20 is aperspective view of an ink jet recording apparatus according to thisembodiment.

In FIG. 20, a recording means (recording head) 411 is mounted on acarriage 412. The carriage 412 is movably guided along a guide shaft413, and is reciprocally moved by a carriage motor 414 via pulleys 415and 416, and a timing belt 417 looped between these pulleys. Asheet-like recording medium 418 such as a paper sheet, a plastic thinplate, or the like is conveyed (fed) in a direction of an arrow A at apredetermined timing and a predetermined pitch along a predeterminedpath by convey rollers (including a pair of rollers) 420 activated by aconvey motor (sheet convey or feed motor) 419. The guide shaft 413 isparallel to the convey rollers 420.

The rear surface of the recording medium 418 is supported by a platen421 on a recording region opposing the recording means, so that therecording medium can oppose the recording means 411 at a predeterminedinterval (e.g., 0.3 to 1.5 mm). When the carriage 412 is moved along therecording medium 418, and ink is discharged from discharge ports(normally, a plurality of discharge ports) of the recording means 411 onthe basis of image information, a recording operation for one line isperformed on the recording medium 418. Upon completion of the recordingoperation for one line, the recording medium 418 is fed at thepredetermined pitch in the direction of the arrow A, thus starting therecording operation for the next line.

A home position HP is set at a predetermined position within a movingrange of the carriage 412 and outside the recording region. A recoveringunit 422 for performing a recover operation for recovering a dischargeerror caused by clogging of ink sticking to, e.g., an ink dischargeportion (discharge ports) of the recording means 411, is arranged at thehome position HP. A cap 423 which is in tight contact with a dischargeport surface of the recording means 411 and covers and closes thedischarge ports when the recording means reaches the home position isarranged on the front surface of the recovering unit 422. The recoveringunit 422 comprises a suction pump (not shown). When no recordingoperation is performed for a predetermined period of time, the carriage412 is moved to the home position HP, and the recovering unit 422 ismoved forward, so that the discharge port surface is closed by the cap423. In this state, the suction pump is operated to draw ink from thedischarge ports by suction, thus executing the recover operation.

The recording means (recording head) 411 comprises electrothermaltransducers for generating heat energy utilized to discharge an ink. Therecording means 411 discharges ink from its discharge ports on the basisof growth and shrinkage of bubbles by film boiling caused by heat energyapplied from the electrothermal transducers, thereby performingrecording.

FIG. 21 is a partial perspective view showing a structure of the inkdischarge portion of the recording means (recording head) 411.

In FIG. 21, a plurality of discharge ports 432 are formed in a dischargeport surface 431 opposing the recording medium 418 at predeterminedintervals (e.g., about 0.5 to 2.0 mm,) and electrothermal transducers(having heating resistors) 435 for generating energy utilized todischarge ink are arranged along wall surfaces of liquid paths 434 forcausing a common liquid chamber 433 to communicate with the respectivedischarge ports 432. In the ink jet recording apparatus shown in FIG.20, the recording means (recording head) 411 is mounted on the carriage412 to have a positional relationship in that the discharge ports 432are aligned in a direction perpendicular to the scanning direction(moving direction) of the carriage 412. In this manner, the recordingmeans (recording head) 411 is arranged, so that desired electrothermaltransducers 435 are activated (energized) on the basis of an imagesignal or a discharge signal, ink in the liquid paths 434 isfilm-boiled, and the ink is discharged from the discharge ports 432based on the film boiling.

In FIGS. 20 and 21, the recording means 411 comprises an atmospheretemperature sensor 424 such as a thermistor for detecting a temperatureof the recording means. In a power-off state of this ink jet recordingapparatus, a time from a previous power-on operation is measured, and atemperature near the recording means is detected at predetermined timeintervals, so that a power-on recover operation of the recording meansis varied depending on the detected temperatures.

FIG. 22 is a block diagram showing an arrangement of a control system ofthe ink jet recording apparatus according to this embodiment.

In FIG. 22, a control unit 440 for controlling the entire recordingapparatus comprises a microprocessor 441, a ROM 442, a RAM 443, a timer444, and an A/D converter 445. The ROM 442 stores, e.g, data necessaryfor control operations of the recording apparatus and programs. The RAM443 holds, e.g., data to be temporarily stored such as detectiontemperatures of the recording means 411, the number of times of recoveroperations upon a power-on operation, and the like. The timer 444measures a time in accordance with an instruction from themicroprocessor 441, and when a designated time elapses, the timer 444outputs an interrupt signal to the microprocessor 441. The A/D converter445 converts a voltage value, e.g., a detection temperature of therecording means 411, from an analog input to a digital output.

In FIG. 22, the control system includes a data transfer device 446 fortransferring recording data to the control unit at a clock rate of apredetermined frequency in response to a trigger signal from the controlunit 440, and an information input portion 447 for outputtinginformation from, e.g., various sensors to the control unit 440. Theoperations of the carriage motor 414 and the convey motor (line feedmotor) 419 are controlled by the control unit 440. Note that thecarriage motor 414 and the convey motor 419 include drivers foractivating these motors.

In FIG. 22, the control system also includes a power-off control unit450 according to the present invention which is operated by powerreceived from a power source 448. The power-off control unit 450comprises a sub CPU (microprocessor) 451, a ROM 452, a RAM 453, a timer454, and an A/D converter 455. The ROM 452 stores, e.g, data necessaryfor control operations of the recording apparatus and programs. The RAM453 holds, e.g., data to be temporarily stored such as detectiontemperatures of the recording means 411, the number of times of recoveroperations upon a power-on operation, and the like. The timer 454measures a time in accordance with an instruction from the sub CPU 451,and when a designated time elapses, the timer 454 outputs an interruptsignal to the sub CPU 451. The A/D converter 455 converts a voltagevalue, e.g., a detection temperature of the recording means 411 from ananalog input to a digital output. A power source 448 of this power-offcontrol unit is a backup type power source including an exchangeablebattery type power source.

Referring to FIG. 22, the temperature sensor 424 for detecting anatmosphere temperature is arranged near an ink discharge portion 449(FIG. 21) of the recording means 411. Detection temperature data fromthe temperature sensor 424 is supplied to both the control unit 440 forthe entire recording apparatus, and the power-off control unit 450.

A control operation in a power-off state of the ink Jet recordingapparatus will be described below.

When the power source is turned off, the sub CPU 451 and the temperaturesensor 424 measure a temperature near the recording head 411, and storesthe measured value as data of 0 minute from the beginning of measurementin the RAM 453. The timer 454 measures a time with reference to thisstorage timing, and the sub CPU 451 and the temperature sensor 424sequentially measure temperatures near the recording means 411 at1-minute intervals. In this case, the detected temperatures are comparedwith a standard temperature (e.g., 15° C.), and parameters such as thenumber of times of detection of temperatures below the standardtemperature, the number of continuous temperatures below the standardtemperature, and the like are stored in the RAM 453.

For example, when 30 minutes going back from a given power-on operationare defined as one cycle, and control is made based on temperaturemeasurement data during this interval, temperatures during a first extraperiod are sequentially erased from the RAM 453 when 30 minutes elapses.In this manner, when the power source is turned on again, a recoveryoperation is controlled with reference to temperature measurement datafor 30 minutes before the power-on operation. If a time interval betweenthe power-off operation and the power-on operation is equal to or lessthan 30 minutes, no data are erased, and control is made using all thetemperature measurement data during this interval as standard data.

FIG. 23 is a graph for exemplifying the temperature measurement data inthe power-off state. FIG. 23 shows data for 30 minutes (-30 minutes tothe power-on operation) before a power-on operation. The "standardtemperature" is a temperature below which ink begins to stick to thedischarge ports, and is set to be, e.g., about 15° C.

FIG. 24 is a flow chart showing a sequence of a recover operation in theink jet recording apparatus according to this embodiment. The recoveroperation of this embodiment will be described in detail below withreference to FIG. 24.

In FIG. 24, when the power source of the recording apparatus is turnedoff in step S401, a control operation by the sub CPU 451 in thepower-off control unit 450 is started. In step S402, a temperaturemeasurement period in a power-off state is set to be a maximum of 30minutes, and a corresponding RAM area is assured. In addition, asampling time (measurement interval) m is set to be, e.g., 1 minute, andthe timer 454 is started.

It is checked in step S403 if one minute has passed in the timer 454. IfYES in step S403, the flow advances to step S404, and the presentatmosphere temperature is detected by the temperature sensor (e.g.,thermistor) arranged in the recording means 411, and the measurementdata is stored in the RAM 453. When the data is stored in the RAM 453,if data for 30 minutes have already been stored, data before 30 minutesor more are erased, so that only data for 30 minutes before the power-onoperation can be stored. In step S405, it is checked if the power sourceof the recording apparatus is turned on. If NO in step S405, the flowreturns to step S403 to repeat the above-mentioned operations.

If it is determined in step S405 that the power source of the recordingapparatus is turned on, the flow advances to step S406, and it ischecked based on data stored in the RAM 453 (30 or less data in thisembodiment) if the number of temperatures exceeding the standardtemperature (e.g., 15° C.) or the number of continuous temperaturesexceeding the standard temperature is larger than a predetermined value.

If it is determined in step S406 that the number of temperaturesexceeding the standard temperature is equal to or larger than thepredetermined value (e.g., 10 times), or that the number of continuoustemperatures exceeding the standard temperature is equal to or largerthan the predetermined value (e.g., 3 times), it is determined that anatmosphere temperature in the power-off state is high, and an ink in thedischarge portion does not so suffer from sticking. The flow advances tostep S407, and a recover treatment is performed for a short period oftime (e.g., 5 seconds) as a recover operation upon a power-on operation.On the other hand, if it is determined in step S406 that the number oftemperatures exceeding the standard temperature is smaller than thepredetermined value (e.g., 10 times), or that the number of continuoustemperatures exceeding the standard temperature is smaller than thepredetermined value (e.g., 3 times), it is determined that theatmosphere temperature in the power-off state is low, and ink in thedischarge portion suffers from sticking. The flow then advances to stepS408, and a recover treatment is performed for a long period of time(e.g., 20 seconds) as a recover operation upon a power-on operation.

With the above-mentioned recover operation, a recover treatment timeupon a power-on operation can be efficiently determined on the basis ofdegree of ink sticking in a power-off state, and a discharge error or arecording error caused by ink sticking can be reliably prevented. Inaddition, ink and a recover treatment time can be prevented from beingwasted. In the recover operation upon a power-on operation, not only arecover time is set, but also the number of times of preliminarydischarge operations may be controlled, or an ink suction force may becontrolled, or temperature control of the recording head 411 may beadjusted. Furthermore, a recovery operation attained by combining theabove-mentioned operations may be performed.

In the embodiment described above, as parameters for determining acontent (time) of a recover operation upon a power-on operation, thenumber of temperatures exceeding the standard temperature, or the numberof continuous temperatures exceeding the standard temperature is used.In place of these parameters, a total value (integrated value) ofdifferences between the standard temperature and measurementtemperatures may be used. For example, if the integrated value is largerthan 0, it can be determined that an average value of atmospheretemperatures in the power-off state is higher than the standard value,and control is made to shorten a recover time. If the integrated valueis smaller than 0 (negative), control can be made to prolong the recovertime, thereby reliably removing ink sticking to the discharge portion.

In the above embodiment, temperatures in the power-off state arecompared with the standard temperature to determine a content of therecover operation upon a power-on operation. For example, only the timerfunction of the power-off control unit 450 is operated to measure apower-off time without reading and storing atmosphere temperature valuesfrom the temperature sensor 424. When the power-off time is very short(e.g., 10 minutes), it is determined that no ink sticking caused by achange in temperature occurs, and control may be made to start arecording operation without performing the recover operation upon apower-on operation. With this control, a time to the beginning ofrecording can be shortened, and a throughput can be further improved.

Contrary to this, when the power-off time is very long (e.g., 10 days),since it is difficult to remove sticking ink by a normal recoveroperation, control may be made to perform a special recover operation(e.g., to continuously perform the normal recover operation four times),thereby preventing a recording error or a discharge error.

In the embodiment described above, a recover operation upon a power-onoperation is varied using atmosphere temperatures of the recording means(recording head) 411 as parameters. In some cases, atmosphere humiditiesmay be detected in place of temperatures, and the content of the recoveroperation upon a power-on operation may be altered using the detectedhumidities as parameters.

In the above embodiment, the present invention is applied to aserial-type ink Jet recording apparatus in which the recording means(recording head) 411 is mounted on the carriage 412 which is moved alongthe recording medium 418. The present invention can also be applied toan ink jet recording apparatus which employs a line recording meanshaving a length corresponding to the entire or partial recording regionin the widthwise direction of a recording medium regardless of the typeof scanning system, and the same effects as described above can beobtained. As the recording means (recording head) in the aboveembodiment, recording means having various structures such as "anexchangeable cartridge type recording means in which a recording headand an ink tank are integrated, a recording means having a structurewherein a recording head and an ink tank are separated and are coupledthrough a coupler or a tube, and the like may be used.

In the above embodiment, the ink jet recording apparatus comprising thesingle recording means (recording head) 411 has been exemplified.However, the present invention can be applied to an ink jet recordingapparatus comprising a plurality of recording means for recording datain different colors, or a gradation recording ink jet recordingapparatus comprising a plurality of recording means having the samecolor but different densities regardless of the number of recordingmeans, and the same effects as described above can be attained.

As can be seen from the above description, in an ink jet recordingapparatus for discharging ink from the recording means to performrecording, a time from a previous power-off operation is measured andtemperatures near the recording means are measured at predetermined timeintervals in a power-off state, so that a recover operation upon apower-on operation of the recording means is altered according to thedetected temperatures. Thus, an ink sticking state upon a power-onoperation can be correctly Judged, and a recover operation upon apower-on operation can be optimized. Thus, an ink jet recordingapparatus which can eliminate a recording error caused by a dischargeerror, prevent wasteful ink consumption and time can be provided.

In addition to the above arrangement, a power-off control unit whichreceives power from a backup power source or battery in a power-onstate, and is started in a power-off state is arranged, and a time fromthe power-off operation is measured by a timer of the power-off controlunit. Thus, an ink jet recording apparatus which can more accuratelycontrol a recover operation in addition to the above effects can beprovided.

The present invention is particularly suitably usable in an ink jetrecording head and recording apparatus for discharging ink by utilizingheat energy. This is because the high density of the picture element andthe high resolution of the recording are possible.

The typical structure and the operational principle of preferably theone disclosed in U.S. Pat. Nos. 4,723,129 and 4,740,796. The principleis applicable to a so-called on-demand type recording system and acontinuous type recording system. Particularly however, the principle issuitable for the on-demand type because the principle is such that atleast one driving signal is applied to an electrothermal transducerdisposed on a liquid (ink) retaining sheet or liquid passage, thedriving signal being enough to provide such a quick temperature risebeyond a departure from nucleation boiling point, by which the thermalenergy is provided by the electrothermal transducer to produce filmboiling on the heating portion of the recording head, whereby a bubblecan be formed in the liquid (ink) corresponding to each of the drivingsignals. By the development and collapse of the bubble, the liquid (ink)is ejected through an ejection outlet to produce at least one droplet.The driving signal is preferably in the form of a pulse, because thedevelopment and collapse of the bubble can be effected instantaneously,and therefore, the liquid (ink) is ejected with quick response. Thedriving signal in the form of the pulse is preferably such as disclosedin U.S. Pat. Nos. 4,463,359 and 4,345,262. In addition, the temperatureincreasing rate of the heating surface is preferably such as disclosedin U.S. Pat. No. 4,313,124.

The structure of the recording head may be as shown in U.S. Pat. Nos.4,558,333 and 4,459,600 wherein the heating portion is disposed at abent portion in addition to the structure of the combination of theejection outlet, liquid passage and the electrothermal transducer asdisclosed in the above-mentioned patents. In addition, the presentinvention is applicable to the structure disclosed in Japanese Laid-OpenPatent Application Publication No. 123670/1984, wherein a common slit isused as the ejection outlet for plural electrothermal transducers, andto the structure disclosed in Japanese Laid-Open Patent Application No.138461/1984 wherein an opening for absorbing the pressure wave of thethermal energy is formed corresponding to the ejecting portion. This isbecause the present invention is effective to perform the recordingoperation with certainty and at high efficiency irrespective of the typeof the recording head.

The present invention is effectively applicable to a so-called full-linetype recording head having a length corresponding to the maximumrecording width. Such a recording head may comprise a single recordinghead and a plural recording head combined to cover the entire width.

In addition, the present invention is applicable to a serial typerecording head wherein the recording head is fixed on the main assembly,to a replaceable chip type recording head which is connectedelectrically with the main apparatus and can be supplied with the ink bybeing mounted in the main assembly, or to a cartridge type recordinghead having an integral ink container.

The provision of the recovery means and the auxiliary means for thepreliminary operation are preferable because they can further stabilizethe effect of the present invention. As for such means, there arecapping means for the recording head, cleaning means therefor, pressingor sucking means, preliminary heating means by the ejectionelectrothermal transducer or by a combination of the ejectionelectrothermal transducer and additional heating element and means forpreliminary ejection not for the recording operation, which canstabilize the recording operation.

As regards the kinds of the recording head mountable, it may be a singlehead corresponding to a single color ink, or may be plural headscorresponding to the plurality of ink materials having differentrecording color or density. The present invention is effectivelyapplicable to an apparatus having at least one of a monochromatic modemainly with black and a multi-color with different color ink materialsand a full-color mode by the mixture of the colors which may be anintegrally formed recording unit or a combination of plural recordingheads.

Furthermore, in the foregoing embodiment, the ink has been liquid. Itmay be, however, an ink material solidified at the room temperature orbelow and liquefied at the room temperature. Since in the ink jetrecording system, the ink is controlled within the temperature not lessthan 30° C. and not more than 70° C. to stabilize the viscosity of theink to provide the stabilized ejection, in usual recording apparatus ofthis type, the ink is liquid within the temperature range when therecording signal is applied. In addition, the temperature rise due tothe thermal energy is positively prevented by consuming it for the statechange of the ink from the solid state to the liquid state, or the inkmaterial is solidified when it is used to prevent the evaporation of theink. In either case, application of the recording signal producingthermal energy, the ink may be liquefied, and the liquefied ink may beejected. The ink may start to be solidified at the time when it reachesthe recording material. The present invention is applicable to such anink material as is liquefied by the application of the thermal energy.Such an ink material may be retained as a liquid or solid material onthrough holes or recesses formed in a porous sheet as disclosed inJapanese Laid-Open Patent Application No. 56847/1979 and JapaneseLaid-Open Patent Application No. 71260/1985. The sheet theelectrothermal transducers. The most effective one for the ink materialsdisclosed above is the film boiling system.

The ink jet recording apparatus may be used as an output terminal of aninformation processing apparatus such as computer or the like, a copyingapparatus combined with an image reader or the like, or a facsimilemachine having information sending and receiving functions.

According to the present invention, at least one side of the four sidesof the orifice plates are not bonded with the front seal plate, andtherefore, even if the front seal is influenced by the difference in thethermal expansions of various elements, the force applied to the orificeplate can be significantly reduced, and the deformation or the crackproduction of the orifice plate of the top plate can be prevented.

Therefore, the cause of print quality can be removed, and therefore theink jet recording head cartridge and an ink jet recording apparatususing the same can be provided which can produce high quality printreliably under various conditions.

While the invention has been described with reference to the structuresdisclosed herein, it is not confined to the details set forth and thisapplication is intended to cover such modifications or changes as maycome within the purposes of the improvements or the scope of thefollowing claims.

What is claimed is:
 1. An ink jet apparatus having a recovery mechanism for performing ink jet recovery operations to recover ink discharge from an ink jet head, said apparatus comprising:timer means for measuring a predetermined time period; control means for selecting and effecting one of plural ink jet recovery operations based on the time period measured by said timer means, each said recovery operation being distinct and independent from each other; and a back-up power source for effecting measurement by said timer means even when a power source of said ink jet apparatus is turned off, wherein said control means resets said timer means in response to completion of an effected recovery operation, and further wherein at least a time period from when the effected recovery operation is completed directly before a turning-off of the power source of said ink jet apparatus to a turning-on of the power source of said ink jet apparatus is measured said control means selects and effects one of the plural recovery operations based on the measured time period, when the power source of said ink jet apparatus is turned on.
 2. An apparatus according to claim 1, wherein one of the plural recovery operations comprises at least a preliminary discharge operation for discharging ink which is not used for recording.
 3. An apparatus according to claim 1, wherein one of the plural recovery operations comprises a suction operation for drawing the ink from a discharge port of the ink jet head using a cap in a state wherein said discharge port is covered with said cap.
 4. An apparatus according to claim 1, wherein one of the plural recovery operations comprises a compression operation for compressing the ink in a passage communicating with a discharge port of the ink jet head, and forcing the discharge port to discharge the ink.
 5. An apparatus according to claim 1, wherein one of the plural recovery operations comprises a wiping operation for wiping a discharge port of the ink jet head and a portion around the discharge port using a blade.
 6. An apparatus according to claim 1, wherein the ink jet head includes an electrothermal transducer for generating heat energy utilized to cause film boiling of the ink so as to discharge the ink from a discharge port.
 7. An ink jet apparatus according to claim 1, wherein said control means includes a recovery table defining at least the plural recovery operations according to the time period from the recovery operation completed just before the turning-off of the power source of said ink jet apparatus to the turning-on of the power source of said ink jet apparatus.
 8. An ink jet apparatus according to claim 1, further comprising measure means for measuring environmental temperature at a point near said ink jet head, said environmental temperature measure means for measuring an environmental temperature change at the point while the power source of said ink jet apparatus is shut off, wherein said control means controls driving of the recovery mechanism based on the environmental temperature measured by said environmental temperature measure means.
 9. An apparatus according to claim 8, wherein when the temperature at the point near said ink jet head is relatively large, the recovery operation is not performed. 